Touch and hover sensing

ABSTRACT

A capacitive sensing apparatus is disclosed. In some examples, the capacitive sensing apparatus includes a sensor control system configured to: during a first scan of the sensor array: transmit a first alternating current (AC) signal concurrently with a second alternating current (AC) signal to the sensor array, transmit the first AC signal to the first electrode of the sensor array, measure a self capacitance at the first input location, and transmit the second AC signal to the second electrode of the sensor array without measuring a self capacitance at the second input location, and during a second scan of the sensor array: transmit the first AC signal concurrently with the second AC signal to the sensor array, transmit the first AC signal to the first electrode of the sensor array without measuring the self capacitance at the first input location, and measure the self capacitance at the second input location.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/083,102, filed Mar. 28, 2016 and published on Jul. 21, 2016 as U.S.Patent Publication No. 2016/0209982, which is a continuation of U.S.patent application Ser. No. 12/501,382, filed Jul. 10, 2009 and issuedon Apr. 26, 2016 as U.S. Pat. No. 9,323,398, the contents of which areincorporated herein by reference in their entirety for all purposes.

FIELD

This relates generally to touch and hover sensing, and in particular, toimproved capacitive touch and hover sensing.

BACKGROUND

Many types of input devices are presently available for performingoperations in a computing system, such as buttons or keys, mice,trackballs, joysticks, touch sensor panels, touch screens and the like.Touch screens, in particular, are becoming increasingly popular becauseof their ease and versatility of operation as well as their decliningprice. Touch screens can include a transparent touch sensor panelpositioned in front of a display device such as a liquid crystal display(LCD), or an integrated touch screen in which touch sensing circuitry ispartially or fully integrated into a display, etc. Touch screens canallow a user to perform various functions by touching the touch screenusing a finger, stylus or other object at a location that may bedictated by a user interface (UI) being displayed by the display device.In general, touch screens can recognize a touch event and the positionof the touch event on the touch sensor panel, and the computing systemcan then interpret the touch event in accordance with the displayappearing at the time of the touch event, and thereafter can perform oneor more actions based on the touch event.

Mutual capacitance touch sensor panels can be formed from a matrix ofdrive and sense lines of a substantially transparent conductive materialsuch as Indium Tin Oxide (no), often arranged in rows and columns inhorizontal and vertical directions on a substantially transparentsubstrate. Drive signals can be transmitted through the drive lines,which can make it possible to measure the static mutual capacitance atthe crossover points or adjacent areas (sensing pixels) of the drivelines and the sense lines. The static mutual capacitance, and anychanges to the static mutual capacitance due to a touch event, can bedetermined from sense signals that can be generated in the sense linesdue to the drive signals.

While some touch sensors can also detect a hover event, i.e., an objectnear but not touching the touch sensor, typical hover detectioninformation may be of limited practical use due to, for example, limitedhover detection range, inefficient gathering of hover information, etc.

SUMMARY

This relates to improved capacitive touch and hover sensing. Acapacitive sensor array can be driven with electrical signals, such asalternating current (AC) signals, to generate electric fields thatextend outward from the sensor array through a touch surface to detect atouch on the touch surface or an object hovering over the touch surfaceof a touch screen device, for example. The electric field can alsoextend behind the sensor array in the opposite direction from the touchsurface, which is typically an internal space of the touch screendevice. An AC ground shield may be used to enhance the hover sensingcapability of the sensor array. The AC ground shield can be positionedbehind the sensor array and can be stimulated with signals having thesame waveform as the signals driving the sensor array. As a result, theelectric field extending outward from the sensor array can beconcentrated. In this way, for example, the hover sensing capability ofthe sensor array may be improved.

Hover sensing may also be improved using methods to detect a hoverposition of an object outside of a space directly above the touchsurface. In particular, the hover position and/or height of an objectthat is nearby, but not directly above, the touch surface (in otherwords, an object outside of the space directly above the touch surface),e.g., in the border area at the end of a touch screen, may be determinedusing measurements of sensors near the end of the touch screen byfitting the measurements to a model. Other improvements relate to thejoint operation of touch and hover sensing, such as determining when andhow to perform touch sensing, hover sensing, both touch and hoversensing, or neither.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure, in accordance with one or more variousembodiments, is described in detail with reference to the followingfigures. The drawings are provided for purposes of illustration only andmerely depict example embodiments of the disclosure. These drawings areprovided to facilitate the reader's understanding of the disclosure andshould not be considered limiting of the breadth, scope, orapplicability of the disclosure. It should be noted that for clarity andease of illustration these drawings are not necessarily made to scale.

FIGS. 1A-1B illustrate an example sensor array and AC ground shieldaccording to embodiments of the disclosure.

FIGS. 2A-2B illustrate example sensor array configurations with andwithout an AC ground shield according to embodiments of the disclosure.

FIG. 3 illustrates an example touch screen according to embodiments ofthe disclosure.

FIG. 4 illustrates an object directly above an example touch screenaccording to embodiments of the disclosure.

FIG. 5 illustrates an object outside of a space directly above anexample touch screen according to embodiments of the disclosure.

FIG. 6 illustrates example capacitance measurements according toembodiments of the disclosure.

FIG. 7 is a flowchart of an example method of determining a hoverposition/height according to embodiments of the disclosure.

FIG. 8 illustrates an example touch and hover sensing system accordingto embodiments of the disclosure.

FIG. 9 illustrates an example touch and hover sensing system accordingto embodiments of the disclosure.

FIG. 10 is a flowchart of an example method of detecting touch and hoverevents according to embodiments of the disclosure.

FIG. 11 is a flowchart of an example method of operating a touch andhover sensing system according to embodiments of the disclosure.

FIG. 12A illustrates an example mobile telephone that can includeimproved capacitive touch and hover sensing according to embodiments ofthe disclosure.

FIG. 12B illustrates an example digital media player that can includeimproved capacitive touch and hover sensing according to embodiments ofthe disclosure.

FIG. 12C illustrates an example personal computer that can includeimproved capacitive touch and hover sensing according to embodiments ofthe disclosure.

DETAILED DESCRIPTION

In the following description of embodiments, reference is made to theaccompanying drawings which form a part hereof, and in which it is shownby way of illustration specific embodiments that can be practiced. It isto be understood that other embodiments can be used and structuralchanges can be made without departing from the scope of the disclosedembodiments.

This relates generally to touch and hover sensing, and moreparticularly, to improved capacitive touch and hover sensing. Forexample, an alternating current (AC) ground shield may be used toenhance the hover sensing capability of a sensor array, such as acapacitive touch sensor array. Electrical signals, such as AC signals,transmitted to a capacitive touch sensor array in a touch screen cangenerate electric fields that extend outward from the sensor arraythrough a touch surface to detect a touch on the touch surface or anobject hovering over the touch surface. The electric field can alsoextend behind the sensor array in the opposite direction from the touchsurface, which is typically an internal space of the touch screendevice. An AC ground shield can be positioned behind the sensor array,and the AC ground shield can be stimulated with signals having the samewaveform as the AC signals, for example. As a result, the electric fieldextending outward from the sensor array can be concentrated, asdescribed in more detail below. In this way, for example, the hoversensing capability of the sensor array may be improved.

Hover sensing may also be improved using methods to detect a hoverposition of an object outside of a space directly above the touchsurface. In particular, the hover position and/or height of an objectthat is nearby, but not directly above, the touch surface (in otherwords, an object outside of the space directly above the touch surface),e.g., in the border area at the end of a touch screen, may be determinedusing measurements of sensors near the end of the touch screen byfitting the measurements to a model, as described in more detail below.Other improvements relate to the joint operation of touch and hoversensing, such as determining when and how to perform touch sensing,hover sensing, both touch and hover sensing, or neither, as described inmore detail below.

FIGS. 1A and 1B show an example embodiment of a capacitive touch andhover sensing apparatus that includes an AC ground shield (also referredto as a “driven shield”).

FIG. 1A shows a portion of a touch and hover sensing apparatus 100 witha sensor array 101 that includes an array of horizontal lines 103 andvertical lines 105. Horizontal lines 103 and vertical lines 105 can be,for example, electrically conductive lines in a self capacitive sensingsystem. In other embodiments, other types of sensing schemes may beused, such as mutual capacitive, optical, ultrasonic, etc. In someembodiments, such as touch screens, for example, lines 103 and/or 105can be formed of substantially transparent conductive materials. In someembodiments, such as trackpads, for example, lines 103 and/or 105 may beformed of a non-transparent conductive material.

Touch and hover sensing apparatus 100 also includes a touch and hovercontrol system 107 that can drive sensor array 101 with electricalsignals, e.g., AC signals, applied to horizontal lines 103 and/orvertical lines 105. The AC signals transmitted to sensor array 101create electric fields extending from the sensor array, which can beused to detect objects near the sensor array. For example, an objectplaced in the electric field near sensor array 101 can cause a change inthe self capacitance of the sensor array, which can be measured byvarious techniques. Touch and hover control system 107 can measure theself capacitance of each of the horizontal and vertical lines to detecttouch events and hover events on or near sensor array 101.

The maximum range of detection can depend on a variety of factors,including the strength of the electric field generated by sensor array101, which can depend on the voltage, i.e., amplitude, of the AC signalsused for detection. However, the AC signal voltage may be limited by avariety of design factors, such as power limitations, impedancelimitations, etc. In some applications, such as consumer electronics ingeneral and portable electronics in particular, the limited maximumvoltage of the AC signals may make it more difficult to design touch andhover sensing systems with acceptable detection ranges.

In this regard, FIG. 1B shows an AC ground shield system that can beused with sensor array 101. The AC ground shield system includes an ACground shield 201 and an AC shield driving system 203. AC ground shield201 can be positioned substantially behind sensor array 101, that is, onthe side of sensor array 101 opposite to the touch and hover detectionside of the sensor array. AC shield driving system 203 can transmit ACsignals to AC ground shield 201 to create an electric field that canhelp concentrate the electric field generated by sensor array 101 in adetection space above sensor array 101 (shown as the z-direction in FIG.1B).

FIGS. 2A and 2B illustrate an example of how the electric fieldgenerated by sensor array 101 may be concentrated by AC ground shield201. FIG. 2A shows a stimulated horizontal conductive line 103 of sensorarray 101 in a configuration without AC ground shield 201. An electricfield 250 extends substantially radially from horizontal conductive line103 in all directions. FIG. 2B illustrates how including AC groundshield 201 with the configuration of FIG. 2A can concentrate electricfield of conductive line 103 into a different electric field 253. InFIG. 2B, horizontal conductive line 103 of sensor array 101 isstimulated in the same way as in FIG. 2A, and AC ground shield 201 isstimulated in a substantially similar way as conductive line 103. Forexample, the AC signals transmitted to AC ground shield 201 can havesubstantially the same waveform as the AC signals transmitted to sensorarray 101, such that the voltage of the AC ground shield can besubstantially the same as the voltage of sensor array 101 at anyparticular time. The stimulation of AC ground shield generates anelectric field 255. FIG. 2B shows electric field 253 concentrated above(in the z-direction) horizontal conductive line 103 due to the operationof AC ground shield 201. In this way, for example, the addition of ACground shield 201 can help boost the detection range of sensor array101.

In addition, AC ground shield 201 can reduce or eliminate the electricfield between sensor array 101 and AC ground shield 201. Moreparticularly, even though the voltages on sensor array 101 and AC groundshield 201 may be changing over time, the change can be substantially inunison so that the voltage difference, i.e., electric potential, betweenthe sensor array and the AC ground shield can remain zero orsubstantially zero. Therefore, little or no electric fields may becreated between sensor array 101 and AC ground shield 201. FIG. 2B, forexample, shows that the space between horizontal conductive line 103 andAC ground shield 201 is substantially free of electric fields in theexample configuration.

FIG. 3 illustrates an example embodiment in which sensor array 101,touch and hover control system 107, AC ground shield 201, and AC shielddriving system 203 are implemented in a touch screen 300. In thisexample, horizontal lines 103 and vertical lines 105 can be electrodesformed of a substantially transparent conductor. FIG. 3 shows a portionof touch screen 300 in which sensor array 101 and AC ground shield 201can be substantially co-located with display circuitry 317, and inparticular, AC ground shield can be positioned substantially betweendisplay circuitry 317 and sensor array 101. A border 301 holds distalends 303 of sensor array 101. The user can view a displayed imagethrough a cover surface 305 and can, for example, touch the coversurface with their fingers and/or hover their fingers near the coversurface in a space 307 directly above sensor array 101 in order toactivate corresponding elements of a graphical user interface (GUI)corresponding to the detected touch events and/or hover events. In thisexample, touch and hover control system 107 transmits AC signals havinga waveform 311 on a transmission line 309 that connects the touch andhover control system to sensor array 101. Touch and hover control system107 also transmits waveform 311 to a memory 313 for storage. Memory 313stores a buffered copy 315 of waveform 311. AC shield driving system 203reads buffered copy 315 of the waveform from memory 313 and generatescorresponding AC signals with waveform 311, which are then transmittedto AC ground shield 201. In this example configuration, sensor array 101can be positioned substantially between AC ground shield 201 and coversurface 305, and AC ground shield 201 operates as described above toconcentrate electric fields in detecting space 307 over cover surface305.

The configuration of AC ground shield 201 may also help to shield sensorarray 101 from other electronics and/or sources of ground, such as fromdisplay circuitry 317 which can be driven by a display driver 319 togenerate an image viewed through cover surface 305. In particular, asdescribed above, AC ground shield 201 can help prevent or reduce anelectric field emanating from sensor array 101 in the direction of theAC ground shield. In the configuration shown in FIG. 3, AC ground shield201 can be positioned between sensor array 101 and other internalelectronics, such as display circuitry 317 and display driver 319.Therefore, AC ground shield 201 can prevent or reduce an electric fieldemanating from sensor array 101 that could reach display circuitry 317and display driver 319. In this way, AC ground shield 201 may helpelectrically isolate sensor array 101 from other internal electronics inthis example configuration, which may reduce undesirable effects such asnoise, stray capacitance, etc. that could interfere with the accuratemeasuring of capacitance changes caused by objects touching/hovering indetection space 307.

Another type of AC shield, a transmission line AC shield 308, is shownin FIG. 3. Transmission line AC shield 308 substantially surrounds aportion of transmission line 309. AC shield driving system 203 also usesbuffered copy 315 to transmit signals with waveform 311 to transmissionline AC shield 308. This can help to shield transmission line 309 byreducing electric fields emanating from the transmission line. However,in contrast to AC ground shield 201, transmission line AC shield 308does not serve to concentrate fields emanating from transmission line309 to boost a range of detection, for example.

FIG. 4 shows a finger 401 hovering in space 307 directly above sensorarray 101. Finger 401 can disturb electric field lines 403 from sensorarray 101.

FIG. 5 shows finger 401 near distal end 303 and outside of space 307.Even though finger 401 is outside of space 307 directly above sensorarray 101, the finger still disturbs some of the field lines 501emanating from some of the sensors of sensor array 101.

FIG. 6 illustrates capacitance measurements 601 representingmeasurements from FIG. 4 and measurements 603 representing measurementsfrom the configuration in FIG. 5. Measurements 601 can represent atypical shape of a set of capacitance measurements of sensors of sensorarray 101 near a touch object such as finger 401 shown in FIG. 4. Inparticular, measurements closer to the center of finger 401 can begreater than measurements further from the center. Therefore, the shapeof measurements 601 can be modeled, for some objects and sensor arrays,with a curve 605, such as a Gaussian curve, for example. Curve 605 canhave a local maximum 607, which can represent the center of finger 401,for example. Curve 605 also has tail ends on either side of localmaximum 607. FIG. 6 also shows measurements 603, which represent the setof capacitance measurements measured by sensors near distal end 303 ofsensor array 101 after finger 401 has traveled outside of space 307,past distal end 303. In this case, measurements 603 represent only atail end 609 of the curve that would be measured if finger 401 wereinside of space 307. In other words, measurements 603 are an incompleteset of measurements, at least as compared to measurements 601.

In typical algorithms used to determine position and/or hover height ofan object directly above a sensor array of a touch screen, for example,a full set of measurements such as measurements 601 can provide enoughdata to determine the position from a determination of local maximum607. In this case, the determination of local maximum 607 can be easilymade because the set of measurements 601 spans local maximum 607. Inother words, local maximum 607 can be within the range of measurements601. On the other hand, measurements 603 represent only tail end 609portion of a complete curve, which does not include direct informationof a local maximum. Thus, while the shape of tail end 609 can be known,the shape of the complete curve that would be measured if sensor array101 extended beyond distal end 303 can be unknown.

FIG. 6 shows one possible estimate of an unknown curve 611 based on aset of unknown measurements 615. Unknown curve 611 and unknownmeasurements 615 are not actually measured, but are provided forpurposes of illustration to show the general idea of how tail endmeasurements caused by an object near a distal end of an array ofsensors and outside of the space directly above the array may be used todetect a hover position and/or hover height of the object. Inparticular, it may be recognized that measurements 603 represent a tailend 609 of unknown curve 611 and at that determining the parameters ofunknown curve 611, and consequently determining unknown local maximum613, can provide information about the hover position and/or height ofthe object. Consequently, a hover position of the object outside of therange of sensor positions of sensor array 101 may be determined based onthe determined local maximum 613.

FIG. 7 shows an example method of detecting a hover position of anobject outside of space 307 using measurements 603. The example methodof FIG. 7, and other methods described herein, may be performed in, forexample, touch and hover control system 107, a general purpose processorsuch as a central processing unit (CPU) (not shown), and/or anotherprocessor, and results may be stored in, for example, memory 313 and/oranother memory (not shown) as one skilled in the art would readilyunderstand in view of the present disclosure. Referring to FIG. 7,measurements 603 can be obtained (701) and fit (702) to a modelincluding a local maximum outside of space 307. A variety of models maybe used, as well as a variety of fitting methods, to fit measurements603 to determine the hover position of finger 401. For example, aGaussian curve may be used as a model of the type of curve to fit tomeasurements 603. In particular, it may be observed from FIG. 6 thatcurve 605, which approximates one set of measurements 601 of finger 401in one location, appears substantially Gaussian-shaped. Therefore, itmay be reasonable to assume that sensor readings made by an objectsimilar to finger 401 will be Gaussian-shaped. In this case, the modelselected to fit measurements 603 can be a Gaussian curve.

Various methods can be used to fit a Gaussian curve to measurements 603.For example, one method that may be used is a maximum likelihoodestimate method. In this case, for example, parameters of a Gaussiancurve, such as maximum height and standard deviation, may be adjusteduntil differences (errors) between the estimated Gaussian curve andmeasurements 603 are minimized. The Gaussian curve with the lowestestimated error can be used to determine unknown local maximum 613,which can represent the position of finger 401 outside of space 307.

In some embodiments, the model used may be another type of curve, forexample a modified Gaussian curve, a custom curve determined fromprevious data, etc. In some embodiments, the model used may not be acurve at all, but may simply be a set of parameters stored in a lookuptable (LUT). In this case, individual sensor measurements may beindividually fit to the values stored in the lookup table, and once thebest match is found, the lookup table can simply return a single valuerepresenting the determined hover position of the object. The hoverposition values in the lookup table can be based on, for example,empirical data of hover positions corresponding to particular sensormeasurements, previously calculated curve modeling, etc.

In some embodiments, other parameters may be used in the determinationof hover position and/or height. For example, if the object's size,conductivity, etc., are known, these parameters may be included whenfitting the measured capacitances to the model. In some embodiments, amodel can be based on a previous set of capacitance measurements of theobject that includes a local maximum.

In some embodiments, information regarding object size, velocity, etc.,may be taken into consideration in determining a model to be used infitting the capacitance measurements. For example, FIGS. 4-6 illustratean example situation in which a finger 401 travels from the middle ofsensor array 101 toward distal end 303 and then past distal end 303 andoutside of space 307. In this example case, the method could record theset of measurements 601 as the model to which measurements 603 will befitted. The measurements 601 may be stored directly into a lookup table,for example. In another embodiment, measurements 601 may be interpolatedto generate a model curve for use in fitting measurements 603.

In some embodiments, other information about finger 401, such as thefinger's velocity, may be used when fitting measurements 603. Forexample, the velocity of finger 401, which may be determined by aseparate algorithm, may be used as a parameter in the model used duringthe fitting process. In this way, a curve or representation ofmeasurements 601 may be tracked as finger 401 travels outside of space307, such that information regarding the local maximum of the curve canbe maintained even though the local maximum may not be directly detectedin measurements 603.

In some embodiments, multiple models may be considered during fitting ofthe measurements. For example, the method may determine that more thanone object is causing the particular capacitance measurements near adistal end of the sensor array, and the method may use more than onemodel and/or fitting method to attempt to fit the capacitancemeasurements to one or more objects and/or types of objects. Forexample, the method may determine that the capacitance measurements arecaused by multiple objects of the same type, such as “three fingers”, or“two thumbs”, etc. The method may determine that the capacitancemeasurements are caused by objects of different types, such as “a fingerand a thumb”, or “a first and a thumb”, etc. The method may determinethat the capacitance measurements are caused by a variety of numbers andtypes of objects, such as “two fingers and a fist”, or “a left thumb, aright finger, and a palm”, etc. The method may fit different models,corresponding to the different number and/or type of objects, todifferent portions of the capacitance measurements. For example, themethod may determine that the capacitance measurements are caused by twoobjects, e.g., a finger that was previously tracked as it moved off ofthe sensor array and an unknown object estimated to be a thumb. In thiscase, the method may attempt to fit the capacitance measurementscorresponding to the finger to previously stored data by fittingindividual sensor measurements to previously stored values in a LUT andfit the capacitance measurements corresponding to the thumb to aGaussian curve using a maximum likelihood estimate of parametersassociated with a thumb. Thus, some embodiments may estimate the numberof objects and the parameters of each object when fitting thecapacitance measurements.

In some embodiments, the position and/or motion of an object near thedistal end of a sensor array and outside of the space directly above thesensor array may be processed as a user input. For example, a positionand/or motion of an object may be processed as an input to a graphicaluser interface (GUI) currently displayed, as an input independent of aGUI, etc.

For example, the method described with reference to FIG. 7 may be usedto determine a user input based on the position and/or motion of one ormore objects including objects near the distal end of a sensor array andoutside of the space directly above the sensor array. The hover positionof an object in a border area outside the sensor array may be measuredmultiple times to determine multiple hover positions. The motion of theobject can be determined corresponding to the multiple measured hoverpositions, and an input can be detected based on the determined motionof the object. For example, a finger detected moving upwards in a borderarea may be interpreted as a user input to increase the volume of musiccurrently being played. In some embodiments, the user input may controla GUI. For example, a finger detected moving in a border area maycontrol a GUI item, such as an icon, a slider, a text box, a cursor,etc., in correspondence with the motion of the finger.

In some embodiments, a user input can be based on a combination ofinformation including the position and/or motion of an object directlyabove the sensor array and the position and/or motion of an object nearthe distal end of the sensor array and outside of the space directlyabove the sensor array. Referring to FIGS. 3-5, for example, a GUI maybe displayed at cover surface 305. The method described above withreference to FIG. 7 may be used, for example, to control the motion of aGUI item as finger 401 travels off of the touch screen. For example,finger 401 may initiate an input direct above sensor array 101 to “drag”an icon displayed by the GUI. The icon may be controlled by displaydriver 319 to move along a path corresponding to the motion of finger401 inside of space 307. If finger 401 is detected to move outside ofspace 307 and to stop at a position near the distal end of sensor array101, display driver 319 can control the icon to continue moving alongthe path of the finger just prior to the finger moving off of the touchscreen. Display driver 319 can cease the motion of the icon when finger401 is detected to move away from its stopped position. This may behelpful to allow dragging and/or pointing actions to be continued evenwhen a finger, for example, moves off of the touch screen.

FIGS. 8-11 describe examples of different hardware, software, andfirmware embodiments that can perform joint operations of touch sensingand hover sensing. For example, in some embodiments, one set of sensorscan be used for hover sensing and another set of sensors can be used fortouch sensing. For instance, electrodes configured for self-capacitancemeasurements can be used for hover sensing, and electrodes configuredfor mutual capacitance measurements can be used for touch sensing. Inthese cases, switching between touch sensing and hover sensing may bedone to save power, reduce interference, etc. In other embodiments, thesame sensors may be shared between hover sensing and touch sensing. Inthese cases, switching may be necessary in order to utilize sharedcircuit elements, for example. Software and/or firmware may control thejoint operation of touch and hover sensing. For example, depending onthe particular configuration, software and/or firmware may determinewhen to switch between touch sensing and hover sensing, e.g., insingle-mode operation, determine when to perform touch and hover sensingconcurrently, e.g., in multi-mode operation, activate different portionsof a sensor to perform touch and/or hover sensing, etc.

FIGS. 8-9 illustrate example embodiments of hardware switching that maybe used to switch between touch sensing and hover sensing.

FIG. 8 shows an example touch and hover sensing system 800 including asensor array 801 that includes touch and hover circuitry 803 and touchcircuitry 805. For example, touch and hover circuitry 803 can be a setof multiple conductive lines that can operate as a self-capacitancesensor to sense hover events, and touch circuitry 805 can be another setof multiple conductive lines that can sense touch events when pairedwith the conductive lines of touch and hover circuitry 803. Therefore,sensor array 801 includes common circuitry that operates in both thetouch sensing phase and the hover sensing phase. A sensor control system807 can operate sensor array 801 to detect both touch and hover, bytransmitting signals corresponding to hover sensing to touch and hovercircuitry 803 only, and by transmitting signals corresponding to touchsensing to touch and hover circuitry 803 and touch circuitry 805.Therefore sensor control system 807 can serve as an integrated touchcontrol system and hover control system, and determine when to switchbetween touch sensing and hover sensing, as described in more detailbelow.

FIG. 9 shows an example touch and hover sensing system 900 including asensor array 901 and a sensor control system 903. Sensor control system903 includes a switching system 905, a touch control system 907, a hovercontrol system 909, and a low-leakage analog switch 911. In operation,switching system 905 determines when switching from touch sensing tohover sensing, and vice versa, should occur and operates low-leakageanalog switch 911 to switch between touch control system 907 and hovercontrol system 909 accordingly. During a touch sensing phase, touchcontrol system transmits an AC signal to sensor array 901 and measures acapacitance of the sensor array resulting from the AC signal. During ahover sensing phase, hover control system 909 transmits an AC signal tosensor array 901 and measures a capacitance of sensor array 901resulting from the AC signal.

FIGS. 10-11 show example methods of joint touch and hover sensing, whichcan be implemented, for example, in software, firmware,application-specific integrated circuits (ASICs), etc.

FIG. 10 shows an example method for detecting a touch event and a hoverevent on or near a touch and hover sensing apparatus, such as touchscreen 300. In a touch detection phase, touch and hover control system107 can transmit (1001) a first AC signal to sensor array 101, and canmeasure (1002) a first capacitance of the sensor array. Touch and hovercontrol system 107 can detect (1003) a touch event based on the firstcapacitance, and store (1004) touch event data, e.g., position, size,shape, gesture data, etc., in a memory. In a hover detection phase,touch and hover control system 107 can transmit (1005) a second ACsignal to sensor array 101, and can measure (1006) a second capacitanceof the sensor array. Touch and hover control system 107 can detect(1009) a hover event based on the second capacitance, and store (1010)hover event data, such as position, height, size, gesture data, etc.

Other operations can be occurring during or in between the touchdetection and hover detection phases. For example, display driver 319may transmit image signals to display circuitry 317 in a display phasethat can be in between the touch sensing phase and the hover sensingphase. During the touch and/or hover sensing phases, AC shield drivingsystem 203 may operate as described above to shield transmission line309 using transmission line AC shield 308, and to boost the electricfield emanating from cover surface 305 using AC shield 201. The touchdetection phase and hover detection phase may occur in any order.

Some embodiments may not be able to sense touch and hover concurrently,i.e., only a single mode of sensing (non-overlapping touch/hoversensing) is possible. In this case, in some embodiments touch sensingand hover sensing may be time multiplexed, that is, touch and hoversensing can be performed during different, non-overlapping periods oftime. Various methods can be implemented for deciding how to timemultiplex the sensing operations, i.e., deciding whether touch sensingor hover sensing (or neither) should be performed at a particular time.

In some embodiments, touch and hover sensing can operate concurrently,i.e., multi-mode sensing. Even if a system can perform multi-mode touchand hover sensing, it may be advantageous to perform single mode sensingin some cases. For example, if either touch sensing or hover sensing isnot needed at a particular time, switching to single mode sensing tosave power may be desirable.

In some embodiments, the operation of touch sensing and hover sensingcan be determined by a fixed schedule. In other embodiments, the timeand duration of touch and hover sensing can be varied dynamically, forexample, by setting the system to operate in one of a number ofoperational modes including the touch sensing mode and the hover sensingmode, and possibly other modes, such as a display mode. For instance,FIG. 11 shows an example method for determining whether to sense touchand/or hover. A touch sensing operation can be performed (1101), and candetermine (1102) whether a touch is detected. If a touch is detected,the system can perform (1103) both touch and hover sensing, either byswitching between the two, or by performing touch and hover sensingconcurrently if the system is capable of multi-mode sensing. Both touchand hover sensing can be performed after a touch is detected because thetouch may indicate a period of user activity during which a user mayperform hover events and touch events.

If a touch is not detected at 1102, the system can perform (1104) hoverdetection, and can determine (1105) whether a hover is detected. If ahover is detected, the system can perform (1103) both touch and hoversensing, because the hover may indicate a period of user activity. If ahover is not detected at 1105, the system can perform (1104) hoverdetection again. As long as a hover is not detected, the system may notneed to perform touch detection, because any approaching object willcause a hover detection before the object can touch down on the sensingsystem.

Other factors may be used to determine whether to detect touch, hover,both or neither. For example, some embodiments may detect an approachingobject during hover sensing and wait until the object gets close to thetouch surface to perform touch sensing. In other words, a distancethreshold can be used to activate touch sensing. In some embodiments,the touch/hover mode may be determined by a particular softwareapplication that may require, for example, touch data but not hoverdata. In some embodiments, the current number and/or position of touchesmay be used as a factor. For example, a small mobile touch screen devicemay alternate between touch sensing and hover sensing until apredetermined number of contacts, e.g., five, touch the touch surface.When five touch contacts are detected, the device can cease detectinghover and can detect only touch because a user is unlikely to use sixthobject to perform a hover, for example.

Some embodiments may be capable of multi-mode operation, i.e.,performing touch sensing and hover sensing concurrently. For example,some embodiments can use frequency multiplexing to combine AC signalsused for touch sensing with different frequency AC signals used forhover sensing. In some embodiments, code division multiplexing of the ACsignals can be used to perform concurrent touch sensing and hoversensing.

Frequency multiplexing and code division multiplexing can allow circuitelements, such as sensing electrodes, to be used to detect touch andhover concurrently. For example, an entire array of sensors may besimultaneously stimulated to detect touch and hover.

In some embodiments, touch sensing and hover sensing may be spacemultiplexed by, e.g., operating one portion of a sensor array for touchsensing and concurrently operating another portion of the sensor arrayfor hover sensing. For example, an AC signal used for touch sensing canbe transmitted to a first group of sensors of the sensor array, and anAC signal used for hover sensing can be transmitted to a second group ofsensors of the array. The groups of sensors may be changed dynamically,such that touch and hover sensing can be performed by different portionsof the sensor array at different times. For example, touch sensing canbe activated for portions of the sensor array on which touches aredetected, and the remaining sensors may be operated to detect hover. Thesystem can track moving touch objects and adjust the group of sensorssensing touch to follow the moving object.

FIG. 12A illustrates an example mobile telephone 1236 that can includetouch sensor panel 1224 and display device 1230, the touch sensor panelincluding improved capacitive touch and hover sensing according to oneof the various embodiments described herein.

FIG. 12B illustrates an example digital media player 1240 that caninclude touch sensor panel 1224 and display device 1230, the touchsensor panel including improved capacitive touch and hover sensingaccording to one of the various embodiments described herein.

FIG. 12C illustrates an example personal computer 1244 that can includetouch sensor panel (trackpad) 1224 and display 1230, the touch sensorpanel and/or display of the personal computer (in embodiments where thedisplay is part of a touch screen) including improved capacitive touchand hover sensing according to the various embodiments described herein.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notby way of limitation. Likewise, the various diagrams may depict anexample architectural or other configuration for the disclosure, whichis done to aid in understanding the features and functionality that canbe included in the disclosure. The disclosure is not restricted to theillustrated example architectures or configurations, but can beimplemented using a variety of alternative architectures andconfigurations. Additionally, although the disclosure is described abovein terms of various example embodiments and implementations, it shouldbe understood that the various features and functionality described inone or more of the individual embodiments are not limited in theirapplicability to the particular embodiment with which they aredescribed. They instead can be applied alone or in some combination, toone or more of the other embodiments of the disclosure, whether or notsuch embodiments are described, and whether or not such features arepresented as being a part of a described embodiment. Thus the breadthand scope of the present disclosure should not be limited by any of theabove-described example embodiments.

What is claimed is:
 1. A capacitive sensing apparatus comprising: asensor array comprising: a first electrode at a first input location;and a second electrode at a second input location adjacent to the firstinput location; and a sensor control system configured to: during afirst scan of the sensor array: transmit the first AC signal to thefirst electrode of the sensor array; measure a self capacitance at thefirst input location; and transmit the second AC signal to the secondelectrode of the sensor array without measuring a self capacitance atthe second input location; and during a second scan of the sensor array:transmit the first AC signal to the first electrode of the sensor arraywithout measuring the self capacitance at the first input location; andmeasure the self capacitance at the second input location.
 2. Thecapacitive sensing apparatus of claim 1, wherein the sensor controlsystem is further configured to: during a third scan of the sensorarray: transmit the first alternating current (AC) signal concurrentlywith the second alternating current (AC) signal to the sensor array;transmit the first AC signal to the first electrode of the sensor array;measure the self capacitance at the first input location; transmit thesecond AC signal to the second electrode of the sensor array; andmeasure the self capacitance at the first input location.
 3. Thecapacitive sensing apparatus of claim 1, wherein the first and secondsignals have a same voltage.
 4. The capacitive sensing apparatus ofclaim 1, further comprising an AC shield electrode, different from thefirst electrode and the second electrode.
 5. The capacitive sensingapparatus of claim 4, wherein the AC shield is electrically isolatedfrom the sensor array.
 6. The capacitive sensing apparatus of claim 1,wherein the first AC signal and the second AC signal are transmittedconcurrently.
 7. The capacitive sensing apparatus of claim 1, whereinthe sensor control system is further configured to: during a mutualcapacitance scan of the sensor array: transmit the first AC signal tothe first electrode of the sensor array; measure a mutual capacitance atthe first input location; transmit the second AC to the second electrodeof the sensor array; and measure the mutual capacitance at the secondinput location.
 8. The capacitive sensing apparatus of claim 1, whereinthe first AC signal has a waveform and the second AC signal is generatedfrom a buffered copy of the waveform.
 9. A method comprising: during afirst scan of a sensor array: transmitting a first alternating current(AC) signal concurrently with a second alternating current (AC) signalto the sensor array; transmitting the first AC signal to a firstelectrode of the sensor array at a first input location; measuring aself capacitance at the first input location; and transmitting thesecond AC signal to a second electrode of the sensor array at a secondinput location without measuring a self capacitance at the second inputlocation, the second input location different from the first inputlocation; and during a second scan of the sensor array: transmitting thefirst AC signal concurrently with the second AC signal to the sensorarray; transmitting the first AC signal to the first electrode of thesensor array without measuring the self capacitance at the first inputlocation; and measuring the self capacitance at the second inputlocation.
 10. The method of claim 9, further comprising: during a thirdscan of the sensor array: transmitting a first alternating current (AC)signal concurrently with a second alternating current (AC) signal to thesensor array; transmitting the first AC signal to the first electrode ofthe sensor array; measuring the self capacitance at the first inputlocation; transmitting the second AC signal to the second electrode ofthe sensor array; and measuring the self capacitance at the first inputlocation.
 11. The method of claim 9, wherein the first and secondsignals have a same voltage.
 12. The method of claim 9, wherein thesensor array comprises an AC shield electrode, different from the firstelectrode and the second electrode.
 13. The method of claim 12, whereinthe AC shield is electrically isolated from the sensor array.
 14. Themethod of claim 12, wherein the first AC signal and the second AC signalare transmitted concurrently.
 15. The method of claim 9, furthercomprising: during a mutual capacitance scan of the sensor array:transmitting the first AC signal to the first electrode of the sensorarray; measuring a mutual capacitance at the first input location;transmitting the second AC to the second electrode of the sensor array;and measuring the mutual capacitance at the second input location. 16.The method of claim 9, wherein the first AC signal has a waveform andthe second AC signal is generated from a buffered copy of the waveform.17. A non-transitory computer-readable storage medium having storedtherein instructions, which when executed by a processor cause theprocessor to perform a method comprising: during a first scan of asensor array: transmitting a first alternating current (AC) signalconcurrently with a second alternating current (AC) signal to the sensorarray; transmitting the first AC signal to a first electrode of thesensor array at a first input location; measuring a self capacitance atthe first input location; and transmitting the second AC signal to asecond electrode of the sensor array at a second input location withoutmeasuring a self capacitance at the second input location, the secondinput location different from the first input location; and during asecond scan of the sensor array: transmitting the first AC signalconcurrently with the second AC signal to the sensor array; transmittingthe first AC signal to the first electrode of the sensor array withoutmeasuring the self capacitance at the first input location; andmeasuring the self capacitance at the second input location.
 18. Thenon-transitory computer readable medium of claim 17, the method furthercomprising: during a third scan of the sensor array: transmitting afirst alternating current (AC) signal concurrently with a secondalternating current (AC) signal to the sensor array; transmitting thefirst AC signal to the first electrode of the sensor array; measuringthe self capacitance at the first input location; transmitting thesecond AC signal to the second electrode of the sensor array; andmeasuring the self capacitance at the first input location.
 19. Thenon-transitory computer readable medium of claim 17, wherein the sensorarray comprises an AC shield electrode, different from the firstelectrode and the second electrode.
 20. The non-transitory computerreadable medium of claim 17, wherein the first AC signal has a waveformand the second AC signal is generated from a buffered copy of thewaveform.